Merge pull request #50 from ngs/master

Added middleman-ogp extension
add middleman-simple-thumbnailer extension
Update
Merge pull request #51 from kubenstein/master

add middleman-simple-thumbnailer extension
Add middleman-google-analytics
Merge pull request #52 from danielbayerlein/middleman-google-analytics

Add middleman-google-analytics
Add middleman-fontcustom
Merge pull request #53 from oame/master

Add middleman-fontcustom
Add entry
Merge pull request #54 from maxmeyer/feature/middleman-presentation

Add entry for middleman-presentation
Add custom extension for others to use. 

Add my custom extension to save others time using the same configuration :: https://github.com/chrishough/middleman-slim-foundation-emberjs-emblemjs
Merge pull request #55 from chrishough/patch-1

Add custom extension for others to use.
Added middleman-blog-similar